Silent allosteric modulators of metabotropic glutamate receptor 5 (mGlu5) occupy allosteric sites but have no intrinsic modulator activity. Thus, such compounds have potential as crucial tools to dissect receptor function and efficacy of novel positive and negative allosteric modulators both in vitro and in vivo. Previous mGlu5 SAMs, VU0365396 and 5MPEP, have low affinity and are therefore more ..

Assay Provider: P. Jeffrey ConnAssay Provider Affiliation: Vanderbilt UniversitySilent allosteric modulators of metabotropic glutamate receptor 5 (mGlu5) occupy allosteric sites but have no intrinsic modulator activity. Thus, such compounds have potential as crucial tools to dissect receptor function and efficacy of novel positive and negative allosteric modulators both in vitro and in vivo. Previous mGlu5 SAMs, VU0365396 and 5MPEP, have low affinity and are therefore limited in their utility as tools (1, 2). The mGlu5 acetylene PAM series is prone to "molecular switches" within the SAR and certain PAMs had previously been shown to exhibit these "molecular switches" when key residues within the the common allosteric site were mutated (3). Thus, this series was predicted to also contain hitherto unappreciated mGlu5 SAMs.To identify and evaluate mGlu5 SAMs, we screened previously identified inactive compounds in an acetylene PAM series at 10uM, to confirm they were inactive. Confirmed "inactives" were then screened in a 3 pt binding assay to rapidly identify compounds that retained appreciable affinity for the common allosteric site and thus categorise these compounds as "SAMs". SAMs with sub-100nM affinities were then selected for determination of binding affinity, using a more rigorous 10 pt inhibition binding curve,